Basic Overview: Potential For Exposure To Oil/Hydraulic Fluid Fumes On Aircraft
Most aircraft are designed and operated to circulate cabin air through the aircraft engine. Engine oil and hydraulic fluid fumes can contaminate the ventilation air supplied to the cabin and flight deck. There are other aircraft air quality concerns, such as the cabin being too hot or too cold/drafty, stagnant ventilation zones, exposure to deicing fluid fumes, ozone gas, fuel fumes, and exhaust. But oil and hydraulic fluid fumes are especially toxic.
When oil or hydraulic fluid contaminates the air supply system, you will notice an unpleasant and unusual smell (“fumes”). Oil fumes are often described as smelling like “dirty socks,” or as being musty, moldy, or foul. Hydraulic fluid fumes often have a distinctive acrid odor. Both types of fumes can contain carbon monoxide gas. Exposure to carbon monoxide – especially inflight where the air contains less oxygen than on the ground - can cause acute symptoms like dizziness/fainting, headache, and slowed thought processes.
Oil fumes are a complex mixture of chemicals, including neurotoxic tricresyl phosphates and other toxins, some of which are listed on the product safety data sheets. Hydraulic fluid fumes are also a complex mixture of chemicals, including tributyl phosphates.
When the fumes contaminate the air supply system, you may see haze or smoke, but typically, you will “only” notice the odor. Still, it is important to recognize, respond to, and report the presence of these types of fumes in the air supply system because they can make you sick.
Print and CARRY THIS GENERAL FUME EVENT INFORMATION CARD and WATCH THIS SLIDE SHOW. Also, keep reading this webpage to find general advice and practical documents.
Tools to recognize and respond to fumes while onboard:
- Print and carry this AFA onboard fumes decision-making flow chart to help you figure out if what you smell is a fume event that demands a response.
- Print and carry this AFA onboard fumes reporting form to make sure you report the key details to the pilots to help them identify the source of the fumes. Complete the form, take a photo of it, and give it to the pilots. At a minimum, report the “FOUR S’s” – source (vents or cabin item?), smell (type, intensity, when it started), site (location in cabin), and symptoms(anyone sick/medical assistance?). And read on…
What to do if you are exposed to air supply system fumes onboard:
If you have reason to believe that you were exposed to either oil or hydraulic fluid fumes in the air coming from the vents in the cabin, report it. Read these answers to frequently asked questions about protocols at AFA-member airlines. If you feel sick, take the following documents to any medical appointments:
- Safety data sheet for the relevant product (oil or hydraulic fluid). Are you an AFA member? Some of the products used at AFA (and other) airlines are listed here, based on best available information. To confirm this information, or to track down missing information, contact your LEC safety chair or email AFA international.
- Two-page Health Care Providers’ Guide that explains to your doctor how these toxins contaminate the cabin air.
- Published medical protocol which provides guidance and best practices on clinical tests.
These AFA-CWA documents will also be helpful:
1) Oil or hydraulic fumes onboard: how to check and what to do;
3) Flight attendant checklist for what to do after an incident;
4) What your doctor needs to know; and
5) Answers to frequently asked questions about onboard smoke and fumes.
Pay attention to unpleasant/unusual odors coming from the air supply system, and report problems.
Document, document, document…
Tell the pilots about irregular conditions in the cabin.
Report the incident to your airline within the requisite time-frame (usually within 48 hours) and keep a copy of any report and response, for your records.
If you are an AFA-CWA member, notify your local union safety representative about air quality problems on a flight, and send your union representative a copy of the documentation.
Still feel sick?
The two-page Health Care Provider’s Guide (link above) is intended to provide doctors with basic information about how oil and hydraulic fluid can contaminate the aircraft air supply, some of the chemicals in the fumes, the associated health effects, recommended medical work ups, and possible treatments. The publication was funded by the Federal Aviation Administration, the lead author is an occupational physician member of the OHRCA research team, and the information is well-referenced. If you require medical appointments with specialists, bring this comprehensive version of the health care providers’ guide to appointments, as necessary, and refer to the AFA-CWA bulletin describing what your doctor should know.
Regarding the information on oil/hydraulic fluid safety data sheets, keep in mind that it is in the interest of the manufacturers to downplay any hazards on these data sheets; example here. Also, make sure your doctor understands the potential for acute and chronic symptoms, even with low-level exposures.
Relevant blood tests?
Prof. Clem Furlong at the University of Washington (UW) in Seattle can no longer accept blood samples from crews/passengers exposed to engine oil fumes because of time/storage/funding limitations, but the research team he leads is still working to develop a suitable blood test to determine exposure to aviation engine oil additives.
Prof. Mohamed Abou-Donia at Duke University is developing a blood test intended to provide objective evidence of brain damage. The test is not specific to toxic exposures, but still may be helpful. More information here.
Wondering if your incident was reported to the aviation authority?
For incidents on US-registered aircraft, search the FAA Service Difficulty website to find out if an airline reported a smoke/fumes incident to the FAA. You will need the incident date and either the operator designator code or the aircraft number. Email AFA for help.
